1. Field of the Invention
The present invention generally relates to a combustion system for improved combustion of solid fuels and, more particularly, to a combustion system which prevents smothering and quenching of the solid fuels during burning while providing improved performance, such as, amongst others, reducing air borne pollutants.
2. Background Description
Residential and commercial solid fuel combustion in the United States and around the world increased sharply after the oil embargoes of the 1970s. This was partly due to the decrease in oil and gas supplies at that time making it quite difficult to obtain these fuels and the simultaneous extreme price increases in such fuels. However, with the steady increase of residential and commercial solid fuel combustion came a steady increase in environmental pollutants, such as copious amounts of particulate matter. This increase in environmental pollutants was especially true with the increased usage of residential coal and wood burning combustion systems (e.g., wood burning stoves).
Due to the increase in environmental pollutants, states began to regulate wood burning stove emissions. Moreover, the United States Environmental Protection Agency (EPA) also began to regulate the emissions of wood burning stoves, and in 1988 all newly built wood burning stoves had to comply with strict EPA regulations. The EPA regulations require airtight wood burning stoves sold after 1988 to pass an emissions certification test where dimensional lumber (e.g., two by fours and four by fours) with enforced 1.5 inch spacing is burned and particulate matter (PM) emissions are measured. Once a wood burning stove passes the EPA standards, it is certified and allowed to be sold within the United States.
However, after many years of field measurements, the field performance of the EPA certified wood burning stoves leaves much room for improvement. Consumer misuse and/or inattention to proper operation, physical degradation of critical components and lack of maintenance, amongst other reasons, cause emissions to be greater than they need be. The poor field performance of many wood burning stoves is further attributed to the fact that the wood burning stoves are designed to burn clean when burning the wood of the certification test, but are generally not as effective when burning cordwood or other solid fuels at a wider range of moisture contents.